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=============================================================================
FreeBSD-SA-00:35                                           Security Advisory
                                                                FreeBSD, Inc.

Topic:          proftpd port contains remote root compromise

Category:       ports
Module:         proftpd
Announced:      2000-08-14
Credits:        lamagra <lamagra@DIGIBEL.ORG>
Affects:        Ports collection prior to the correction date.
Corrected:      2000/07/28
Vendor status:  Updated version released
FreeBSD only:   NO

I.   Background

proftpd is a popular FTP server.

II.  Problem Description

The proftpd port, versions prior to 1.2.0rc2, contains a vulnerability
which allows FTP users, both anonymous FTP users and those with a
valid account, to execute arbitrary code as root on the local machine,
by inserting string-formatting operators into command input, which are
incorrectly parsed by the FTP server.

This is the same class of vulnerability as the one described in
FreeBSD Security Advisory 00:29, which pertained to the wu-ftpd port.

The proftpd port is not installed by default, nor is it "part of
FreeBSD" as such: it is part of the FreeBSD ports collection, which
contains nearly 3700 third-party applications in a ready-to-install
format. The ports collections shipped with FreeBSD 3.5 contains this
problem since it was discovered after the release, but FreeBSD 4.1 did
not ship with the proftpd package (and the port was disabled to
prevent building) because the vulnerability was known but not yet
fixed.

FreeBSD makes no claim about the security of these third-party
applications, although an effort is underway to provide a security
audit of the most security-critical ports.

III. Impact

FTP users, including anonymous FTP users, can cause arbitrary commands
to be executed as root on the local machine.

If you have not chosen to install the proftpd port/package, then your
system is not vulnerable to this problem.

IV.  Workaround

Deinstall the proftpd port/package, if you you have installed it.

V.   Solution

One of the following:

1) Upgrade your entire ports collection and rebuild the proftpd port.

2) Deinstall the old package and install a new package dated after the
correction date, obtained from:

ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-3-stable/ftp/proftpd-1.2.0rc2.tgz
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-4-stable/ftp/proftpd-1.2.0rc2.tgz
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/alpha/packages-4-stable/ftp/proftpd-1.2.0rc2.tgz
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-5-current/ftp/proftpd-1.2.0rc2.tgz
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/alpha/packages-5-current/ftp/proftpd-1.2.0rc2.tgz

NOTE: It may be several days before updated packages are available.

3) download a new port skeleton for the proftpd port from:

http://www.freebsd.org/ports/

and use it to rebuild the port.

4) Use the portcheckout utility to automate option (3) above. The
portcheckout port is available in /usr/ports/devel/portcheckout or the
package can be obtained from:

ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-3-stable/devel/portcheckout-2.0.tgz
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-4-stable/devel/portcheckout-2.0.tgz
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/alpha/packages-4-stable/devel/portcheckout-2.0.tgz
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-5-current/devel/portcheckout-2.0.tgz
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/alpha/packages-5-current/devel/portcheckout-2.0.tgz

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